1. Field of the Invention
The present invention relates to a stabilizer effectiveness control device in which the apparent torsion rigidity of a stabilizer provided between left and right wheels is changed by an actuator.
2. Description of the Related Art
A device is known in which the apparent torsion rigidity of a stabilizer comprising a torsion bar is changed by using an electromagnetic actuator to thereby control change in attitude of a vehicle which is turning (refer to Japanese Unexamined Patent Publication (kokai) No. HEI 4-191114). In a control device like this, it is common practice to control the output of the actuator based mainly on a lateral acceleration value.
In the above conventional apparatus, the control device controls the actuator so that it is contracted/expanded in a direction in which a roll angle generated while the vehicle is turning is cancelled. Specifically, an actuator is normally mounted at one or both ends of a stabilizer and it is controlled such that the actuator so mounted generates a force that can counter a load applied to an outside wheel while the vehicle is turning in response to a running speed. Thus, with this construction, when the vehicle is running at high speeds, a roll angle is controlled so as to be small to increase the rigidity to thereby improve the road holding feeling of the tire, while running at low speeds, the rigidity is controlled so as to be slightly lowered to improve the riding comfort.
However, if a large lateral acceleration or yaw rate is generated not from a high vehicle speed but from a sharp turn of the vehicle, it is desirable to stabilize the vehicle behavior. Conversely, in the case where the lateral acceleration or yaw rate remains small even when the vehicles run at high speeds, or the vehicle runs in a stable fashion even at high speeds, it is desirable that importance is attached to the riding comfort.
It is an object of the present invention to provide a stabilizer effectiveness control device that can improve not only the running stability but also the riding comfort of a vehicle while it is turning.
According to the present invention, a stabilizer effectiveness control device comprises: an actuator for changing an apparent torsion rigidity of a stabilizer provided between left and right wheels; control means for controlling an output of said actuator; and means for detecting the degree of sharpness of a turn when a vehicle is turning; wherein said actuator is driven and controlled in response to the degree of sharpness of a turn when the vehicle is turning so as to change the apparent torsion rigidity of said stabilizer. According to this construction, in an area where the degree of sharpness of a turn (for instance, actual or estimated lateral acceleration or yaw rate) is small, the change in attitude of a vehicle body is controlled by the actuator 1 such that importance is attached to the riding comfort, and as the degree of sharpness of a turn gets greater, the change in attitude of the vehicle is then controlled such that the actuator 1 having a narrow movement range bottoms and that importance is placed on the running stability provided by the rigidity intrinsic in the stabilizer R.
Further, according to the present invention, a stabilizer effectiveness control device comprises: an electromagnetic actuator for changing an apparent torsion rigidity of a stabilizer provided between left and right wheels of at least one of front and rear wheels; control means for controlling an output of said actuator; bottoming detecting means for detecting that said actuator reaches an extremity of a movable range thereof; wherein the movable range of said actuator is made narrower than a movable range of said left and right wheels; and energizing of said actuator is stopped when said actuator reaches the extremity of the movable range thereof. According to this construction, the vehicle body attitude change (rolling) when the roll angle is small is controlled by the actuator 1, while when the roll angle is large, the actuator first bottoms and thereafter the vehicle body attitude change is controlled by the rigidity intrinsic in the stabilizer, when energizing of the actuator is stopped.